Fluid flow control elements

ABSTRACT

A fluid flow control element for use in apparatus for reciprocating a working piston in a pneumatic drive system includes a plurality of orifices interconnected within the element by passages through which flow is controlled by means of two cap-shaped seals. The seals are arranged in the spaces defined by two pairs of opposed generally conical surfaces. The apparatus includes a directional control valve 3/2 arranged to connect one of the orifices either to a source of pneumatic pressure or to atmosphere and a pressure reservoir connected to another orifice. Two further orifices are connected to opposite ends of a cylinder in which the working piston moves. The arrangement provides for control of the working piston by means of the directional control valve 3/2.

United States Patent '[191 Nussbaumer Nov. 26, 1974 FLUID FLOW CONTROL ELEb [ENTS Primary ExaminerEdgar W. Geoghegan Assistant Examiner-William F. Woods 75 In ento Thomas N ssbaumer, Z 1 V r Switzerlan: ug Attorney, Agent, or FirmMcGlew and Tuttle [73] Assignee: Adeola AG, Zug, Switzerland ABSTRACT "I [22] F1 ed Nov 1972 A fluid flow control element for use in apparatus for [211 App]. No; 310,008 reciprocating a working piston in a pneumatic drive system includes a plurality of orifices interconnected within the element by passages through which flow is [30] Forelgn Apphatlmln Priority Data controlled by means of two cap-shaped seals. The swltzeflmd 17398/71 seals are arranged in the spaces defined by two pairs of opposed generally conical surfaces. The apparatus 2% 91/461 i includes a directional control valve 3/2 arranged to g 1 connect one of the orifices either to a source of pneu- 1 o earc 137 96 b matic pressure or to atmosphere and a pressure reservoir connected to another orifice. Two further orifices are connected to opposite ends of a cylinder in which [56] References C'ted the working piston moves. The arrangement provides UNITED STATES PATENTS for control of the working piston by means of the di- 3,076,477 2/1963 Brandenberg 91/461 rectional COntrOl valve 3/2. 3,093,153 6/1963 Horowitz 137/102 10 Claims, 3 Drawing Figures 1 FLUID FLOW CONTROL ELEMENTS This invention relates to a fluid flow control element and to apparatus for reciprocating a piston in a fluid drive system, the apparatus including a fluid flow control element. I

BACKGROUND OF THE INVENTION In order to reciprocate a piston in a pneumatic drive system, use is normally made of a mechanically actuated directional control valve 5/2, by means of which compressed air can be applied optionally to one of the two piston faces and at the same time the space on the other side of the piston can be connected to the atmosphere. Such arrangements are usually suitable when the distance from the directional control valve 5/2 valve to the drive system is short. However, if this distance is long the slow discharge of air into the atmosphere, resulting from the length of pipe necessary between the valve and the cylinder in which the piston acts, prevents rapid displacement of the piston under the action of the compressed air since the difference between the pressures at the two faces of the piston is too small. Where this particular problem exists, the disadvantage may be overcome by the use of solenoid valves arranged directly alongside the drive system. The electrical actuating member can then be placed at any convenient position. This arrangement suffers from the not inconsiderable disadvantage that electrical conductors are necessary in addition to the pneumatic pipes, so that the assistance of an electrician is necessary when carrying out installation, conversion and repair operations, and in many applications additional difficulties occur as a result of the safety measures that may be prescribed in premises that are damp or carry an explosion risk, for example. Electrical arrangements are therefore often not'used and relatively slow operation of the pneumatic drive system is accepted.

In an unpublished proposal, apparatus for reciprocating a working piston avoids these disadvantages by utilizing a directional control valve 3/2 and a control element which element includes a differential piston having faces of different cross-sectional area and an intermediate reduced connecting part. The piston is displaceable in a bore comprising three stepped portions and each end of the bore is provided with a connecting orifice, the orifice at the narrower end being for direct connection to a compressed air source and that at the wider end being connected by way of a control pipe to the directional control valve 3/2. The valve itself is connected to a compressed-air source, the arrangement being such that the wider end of the bore is connected to the compressed-air source or to an air-discharge orifice depending upon the position of the directional control valve 3/2. That part of the stepped bore of largest diameter is provided with a bypass. An air-release opening communicates with that zone of the bore of medium diameter, and two orifices, each for connecting to the piston and cylinder device, are so arranged that, at each end position of the differential piston, one of the two connecting orifices communicates with the connecting orifice at the end of the bore adjacent to it, while the other communicates with the air-release opening. Although in this arrangement the control element can be fitted as close as possible alongside the drive system, the directional control valve 3/2 is connected to it by a single pipe which can be located at a relatively great distance without incurring the previous disadvantage since the air escapes directly from the control element. This unpublished apparatus, however, suffers from the disadvantage that its application is limited. This arises since a large number of O-rings are used for providing a seal between the differential piston and its guide, and this naturally causes large frictional resistance. Thus, to ensure reliable operation, a minimal difference between the working pressure and atmospheric pressure must be exceeded in order always to move the differential piston into its end positions without delay. Furthermore, two pressure leads running from the actuating valve to the control element are required for this equipment.

SUMMARY OF THE INVENTION The present invention seeks to overcome all these disadvantages. Accordingly the invention provides a fluid flow control element including a body, first and second pairs of opposed generally conical surfaces formed within the body, a first space defined between the first pair of opposed surfaces and a second space defined between the second pair of opposed surfaces, and a passage formed in the body and terminating in the central region of each of the surfaces. A cap-shaped seal is received in the first space and a further capshaped is received in the second space, each of the seals being displaceable by fluid pressure and adapted to seal either of the passages terminating in the surfaces defining the respective space. The body includes a first outlet leading to the passage terminating in one surface of the first pair of opposed surfaces, a second outlet connected to the passage terminating in the other of the first pair of opposed surfaces, and a third outlet connected to the first space. The first space is also connected to the passage terminating in one surface of the second pair of opposed surfaces. The body has a fourth outlet connected to said second space, a fifth outlet connected to the passage terminating in the other surface of the second pair of opposed surfaces, a sixth outlet, and a further passage connected to the sixth outlet, this further passage being connected to the other passage connected to the fifth outlet. A valve seat is formed in the further passage and a valve element is adapted to seat on the valve seat and block the further passage. A rod connects the valve element to said capshaped seal in the second space, so that the position of the valve element in the further passage depends on the position of the cap-shaped seal in the second space.

The invention also provides apparatus for reciprocating a piston in a fluid drive system, including the fluid flow control element of the invention, a directional control valve 3/2 having an in-out orifice, the orifice being connected for fluid flow to or from the first outlet of the control element, a pressure reservoir, 21 fluid line connecting the pressure reservoir to the fourth outlet, and a piston-and-cylinder, said third and fifth outlets being connected to opposite ends of the cylinder.

It should be understood that use of the term outlet" in relation to the present fluid flow control elements is not intended to necessarily imply the direction or intended direction of fluid flow.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be further described by way of example only with reference to the accompanying drawings in which:

FIG. 1 shows a longitudinal section through a fluid flow control element of the invention and illustrates diagrammatically apparatus comprising the element connected to a working cylinder, a compressed-air reservoir and a 3/2-way valve, the apparatus being in a first working position,

FIG. 2 shows a longitudinal section through the apparatus of FIG. 1 in a second working position, and

FIG. 3 shows a transverse section on the line III-III of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The control element illustrated in FIG. 1 is of substantially cylindrical form. It comprises an outer hollow cylindrical case 1 which has four openings la, lb, 1c, 1d, extending through its periphery. Firmly fitted in one of its ends is a hollow member 2 of generally cylindrical form and having an outside diameter which corre' sponds to the inside diameter of the case 1. This hollow member 2 has an O-ring 2a around its outer circumference for providing a seal between the member and the inner surface of the case. The member 2 is retained in the case 1 by a snap ring 2b. The outer end of the hollow member 2 is reduced to form an internally threaded pressured-pipe union 2c. Internally of the union 2c the inner surface of the member 2 widens at an included angle of about 90 to form a conical bearing face 2d leading into a cylindrical surface 22. The member 2 occupies approximately one-fourth of the length of the case I.

Fitted adjacent the member 2 in the interior of the case I is another hollow member 4 consisting of two cylindrical portions 4a, 4b of different diameters, and a separating wall. The larger diameter cylindrical portion 4a fits in the case I and carries on its outer surface three sealing rings 40. At that end of the portion 4a remote from the member 2 is an annular channel 4d which, with the inner wall of the case 1, forms an annular passage. Terminating in this channel 4d and distributed around its periphery are bores 4e extending through the wall of the cylinder portion 4a. The channel 4d also connects with the bore of an internally threaded pressure-pipe union, constituting opening lb, located in the wall of the case I. The inner wall of the portion 4a is cylindrical at its end remote from member 2 but then tapers inwardly at an included angle of approximately 90 to from a conical bearing face 4fleading into a further cylindrical bore of smaller diameter. The hollow cylinder portion 4b of smaller diameter is coaxially connected to the cylinder portion 4a.by a separating wall. The cylinder 412 extends into the cylinder portion of member 2 defined by surface 2e. The end face of cylinder portion 4b is tapered parallel with the bearing face 2:! and likewise takes the form ofa conical bearing face 4g. The cylindrical portion 4b has a central bore extending from the face 4g as far as the level of the median ()-ring 40. In this way, this bore is separated from the interior of the cylinder portion 4a which extends about as far as the midway point along the hollow member 4.

Provided in the outside periphery of the cylinder 4a is a channel which, together with the inner wall of the case 1, forms an annular passage Sb into which run bores 4h extending through the wall of the cylinder 4a, for the purpose of communicating with the interior of the cylinder. Also communicating with the passage 5b is the opening lc which is formed in the wall of the case 1. This opening is connected to a chamber 12b on one side ofa piston 12a working in a cylinder 12 of a pneumatic system. The smaller cylinder 4b contains two diametrically opposite bores 41 which are so arranged that they directly connect the interior of the cylinder 4b to an annular passage 4k formed between the member 2 and casing l. The outlet 1a fitted with a noise-reducing filter insert le is formed in the casing l in communication with the passage 4k. The cylindrical space enclosed by the inner surface 26 is connected to the annular passage 5b by six parallel connecting bores 5a which pass through the member 4.

A further hollow member 6 is connected to the free edge of the larger cylinder 4a of member 4 and an O- ring 6b is fitted to provide a seal between a cylindrical outer wall of the lower part 6a of the member 6 and the inner wall of the case 1. An annular passage 60 between the part 6a and the case 1 is arranged in communication with opening 1d in the case 1. Peripherally distrib uted bores 6d extend through the wall of the part 6a to the passage 6c. The opening 1d is connected to the chamber 120 on the other side of the piston 12a. A portion 6e of the member 6 which extends into the interior of the cylinder portion 4a is tapered and terminates in a cylindrical tube, the end face of which is chamfered parallel with the bearing face 4f and is likewise formed as a conical bearing surface 6f. The outer wall of the tubular portion 6c is of such diameter that it forms, with the inner wall ofthe cylinder portion 4a, a passage 5c which communicates with the channel 4d by way of the bores 4e.

A hollow and substantially cylindrical valve carrier 7, fitted in the bore of the case 1 by means of a flange 7a and sealed by means of an O-ring 7b, is located directly adjacent the hollow member 6. The outer side of the flange 7a of the valve carrier is secured in the case I by means ofa snap ring 70. The outer end ofthe valve carrier 7 projects slightly beyond the end face of the case I and has a discharge orifice 8a fitted with a noisereducing filter 8 which is retained in the orifice by a snap ring 7d cooperating with a shoulder 76 formed in a central boreof the carrier 7. On the side of the flange 7a facing the hollow member 6, the valve carrier 7 forms the inner wall of the annular passage 5d leading into the bores 6d. The central bore of the valve carrier 7 has a cylindrical valve seat 7]". A corresponding valve member includes a cylindrical rod 9, which extends axially through the valve seat 7f into the interior of the valve carrier and also through the hollow member 6 into the conical interior part of the larger cylinder por tion 4a, and a sealing ring 9a which is bonded on to a carrier ring 9b screwed on to the rod 9 and held in position by means of the nut 90. Both ends of rod 9 are screw-threaded. The region between the two bearing faces 4fand 6fcontains a rubber or plastics cap-shaped seal 10, having a lipped edge 10a, and a metal cap 10b. The rod 9 projects through the common central bore of the seal 10 and cap 10b and is secured thereto by means of two lock-nuts 9d and 9e. It should also be noted that a cap-shaped seal 11, also having a lipped edge 11a, is located between the two bearing faces 2d and 4g.

In order to facilitate assembly of the control element, it is advantageous to manufacture the various hollow members 2, 4, 6 separately and then to insert them in the case 1, but it is also possible for one or more of these inner members to be made integrally with the case.

In FIGS. 1 and 2, the working cylinder 12 and its piston 12a, a directional control valve 3/2 13 and a pressure reservior 14 are illustrated diagrammatically as connected to the control element. The directional control valve 3/2 13 has three connections, of which a compressed-air supply line 13a and a pressure exhaust line 13c can be alternately connected to an in-out orifice 13b which is connected by way of a pipe 13a to the control element. To initiate the working stroke of the piston 120, the directional control valve 3/2 13 is so set that it connects the pressure union 20 to a compressedair supply, not shown, by way of the pressure pipe 13a, orifice 13b and line 13d. The pipe 13a may be relatively long and does not need to be of particularly large crosssection. The compressed air then passes through the union 20 into the control element. The cap-shaped seal 11 between the faces 2d and 4g is pressed against the bearing face 4g so that a gap is created between the seal 11 and the bearing face 2d, through which gap the compressed air flows into the passages 5a and 5b and thence through the connecting orifice or opening into the working chamber 12b of the cylinder 12. The piston 12a is moved by the air into the position illustrated in FIG. 1. Part of the compressed air does not flow into the working cylinder 12, but passes from the passage 5b through the bores 411 and into the upper inner compartment of the larger cylinder portion 4a. There it strikes the seal 10 and presses this against its bearing face 6f. The rod 9 connected to the seal 10 is thus pushed downwards and the valve ring 9a is removed from its seat 7]". In this way the air flowing from the working chamber 12c of the cylinder 12 by virtue of the movement of piston 120 can escape extremely rapidly into the atmosphere through the connecting orifice Id, the passage 6( and the bores 6d associated therewith, the passage 5d, the valve 7], 9a and the interior of the valve carrier 7, the air passing out of the element through the noise-reducing filter 8 in outlet 8a. Compressed air passing from the passage 5b flows through the cavity formed between the seal 10 and the bearing face 4f and into the chamber 5c. From here it passes through the bores 4e into passage 40', and hence through the outlet in union lb and the pressure pipe 140 into the compressed-air reservoir 14. Flow into the reservoir 14 continues until a condition of balance has been reached.

For initiation of the idling stroke of the working piston 1211, the valve 13 is set so that it connects the pipe 130 directly to exhaust through line 13c. This situation is illustrated in FIG. 2. The seal 11 is then pressed against its upper face 2d by the excess pressure obtaining in the control element, so that a cavity is now formed between the seal and its lower bearing face 4g. The air flowing from the working chamber 12b of the cylinder can therefore pass through the connecting orifice 1c, the passages 5b and 5a and the cavity between the seal 11 and its bearing face 4g and into the interior bore of the smaller cylinder part 4b. From there its path lies through the bores 4i, passage 4k and filter 1e, secured in the discharge outlet la, and into the atmosphere.

At the same time the compressed air in the interior of the cylinder 40 escapes through the bores 4/1, so that the pressure from the air in the compressed-air reservoir l4 presses the seal 10 against its bearing face 4f,

and the rod 9 connected to the seal 10 closes the valve 7f, 90. The air in the compressed-air reservoir 14 now flows into the passage 5d by way of the union lb, the passage 50 and the cavity now existing between the seal 10 and its lower bearing face 6f, and from the passage 5d the air passes through the bores 6d and the connecting opening 1d and into the chamber 120 of the working cylinder 12 so that it pushes the piston 12a back into the initial position, as shown in FIG. 2.

It should be noted that, in the terms used herein to define the invention and with reference to the specific embodiment of fluid control element described herein by way of example, the first pair of opposed generally conical surfaces are faces 2d, 4g and the second pair of opposed generally conical surfaces are faces 4f, 6f. Similarly the first outlet is at 20, the second outlet is at In, the third outlet is at 10, the fourth outlet is at lb, the fifth outlet is at 1d, and the sixth outlet is at 8a. It should also be noted that in the specific embodiment outlets 2c and 1a are equivalent.

I claim:

l. A fluid flow control element including a body, first and second pairs of opposed generally conical surfaces formed within said body, a first space defined between said first pair of opposed surfaces and a second space defined between said second pair of opposed surfaces, a passage terminating in the central region of each of said surfaces, a cap-shaped seal received in said first space and a further cap-shaped seal received in said second space, each of said seals being displaceable by fluid pressure and adapted to seal either of said passages terminating in the surfaces defining the respective space, said body including a first outlet leading to the passage terminating in one surface of said first pair of opposed surfaces, a second outlet connected to the passage terminating in the other of said first pair of opposed surfaces, a third outlet connected to said first space, said first space being also connected to the passage terminating in one surface of said second pair of opposed surfaces, a fourth outlet connected to said second space, a fifth outlet connected to the passage terminating in the other surface of said second pair of opposed surfaces, a sixth outlet, and a further passage connected to said sixth outlet, said further passage being connected to said other passage connected to the fifth outlet, and a valve seat in said further passage and a valve element adapted to seat on said valve seat and block said further passage, and a rod connecting said valve element to said cap-shaped seal in said second space, so that the position of said valve element in said further passage depends on the position of said capshaped seal in said second space.

2. A fluid flow control element according to claim 1 wherein said body is constituted by a hollow main body, and at least two hollow members tightly inserted in said main body, at least one pair of opposed surfaces being formed by one surface on one member and one surface on another member.

3. A fluid flow control element according to claim 1 wherein said body is constituted by a hollow main body, at least one of said generally conical surfaces being formed integrally as part of said main body.

4. A fluid flow control element according to claim 1, wherein each of said cap-shaped seals extends beyond the periphery of the adjacent inner opposed conical surface, one seal being arranged to be moved by excess pressure applied to the first space through the third outlet and the other seal being arranged to be moved by excess pressure applied to the second space through the fourth outlet.

5. Apparatus for reciprocating a piston in a fluid drive system, including a fluid flow control element according to claim 1, a control valve 3/2 having an in-out orifice, said orifice being connected for fluid flow to or from said first outlet of the control element, a pressure reservoir, 21 fluid line connecting said pressure reservoir to said fourth outlet, and a piston-and-cylinder, said third and fifth outlets being connected to opposite ends of said cylinder.

6. Apparatus according to claim 5 wherein said body of said fluid flow control element is constituted by a hollow main body, and at least two hollow members tightly inserted in said main body, at least one pair of opposed surfaces being formed by one surface on one member and one surface on another member.

7. Apparatus according to claim 5 wherein said body of said fluid flow control element is constituted by a hollow main body, at least one of said generally conical surfaces being formed integrally as part of said main body.

8. Apparatus according to claim 5, wherein each of said cap-shaped seals of said fluid control'element extends beyond the periphery of the adjacent inner opposed conical surface, one of said seals being arranged to be moved by excess pressure applied to the first space through the third outlet and the other of said seals being arranged to be moved by excess pressure applied to the second space through the fourt outlet.

9. Apparatus according to claim 5 wherein said second and sixth outlets of the fluid flow control element are fitted with noise reducing filters.

10. Apparatus according to claim 5 wherein said fluid is air. 

1. A fluid flow control element including a body, first and second pairs of opposed generally conical surfaces formed within said body, a first space defined between said first pair of opposed surfaces and a second space defined between said second pair of opposed surfaces, a passage terminating in the central region of each of said surfaces, a cap-shaped seal received in said first space and a further cap-shaped seal received in said second space, each of said seals being displaceable by fluid pressure and adapted to seal either of said passages terminating in the surfaces defining the respective space, said body including a first outlet leading to the passage terminating in one surface of said first pair of opposed surfaces, a second outlet connected to the passage terminating in the other of said first pair of opposed surfaces, a third outlet connected to said first space, said first space being also connected to the passage terminating in one surface of said second pair of opposed surfaces, a fourth outlet connected to said second space, a fifth outlet connected to the passage terminating in the other surface of said second pair of opposed surfaces, a sixth outlet, and a further passage connected to said sixth outlet, said further passage being connected to said other passage connected to the fifth outlet, and a valve seat in said further passage and a valve element adapted to seat on said valve seat and block said further passage, and a rod connecting said valve element to said cap-shaped seal in said second space, so that the position of said valve element in said further passage depends on the position of said cap-shaped seal in said second space.
 2. A fluid flow control element according to claim 1 wherein said body is constituted by a hollow main body, and at least two hollow members tightly inserted in said main body, at least one pair of opposed surfaces being formed by one surface on one member and one surface on another member.
 3. A fluid flow control element according to claim 1 wherein said body is constituted by a hollow main body, at least one of said generally conical surfaces being formed integrally as part of said main body.
 4. A fluid flow control element according to claim 1, wherein each of said cap-shaped seals extends beyond the periphery of the adjacent inner opposed conical surface, one seal being arranged to be moved by excess pressure applied to the first space through the third outlet and the other seal being arranged to be moved by excess pressure applied to the second space through the fourth outlet.
 5. Apparatus for reciprocating a piston in a fluid drive system, including a fluid flow control element according to claim 1, a control valve 3/2 having an in-out orifice, said orifice being connected for fluid flow to or from said first outlet of the control element, a pressure reservoir, a fluid line connecting said pressure reservoir to said fourth outlet, and a piston-and-cylinder, said third and fifth outlets being connected to opposite ends of said cylinder.
 6. Apparatus according to claim 5 wherein said body of said fluid flow control element is constituted by a hollow main body, and at least two hollow members tightly inserted in saiD main body, at least one pair of opposed surfaces being formed by one surface on one member and one surface on another member.
 7. Apparatus according to claim 5 wherein said body of said fluid flow control element is constituted by a hollow main body, at least one of said generally conical surfaces being formed integrally as part of said main body.
 8. Apparatus according to claim 5, wherein each of said cap-shaped seals of said fluid control element extends beyond the periphery of the adjacent inner opposed conical surface, one of said seals being arranged to be moved by excess pressure applied to the first space through the third outlet and the other of said seals being arranged to be moved by excess pressure applied to the second space through the fourt outlet.
 9. Apparatus according to claim 5 wherein said second and sixth outlets of the fluid flow control element are fitted with noise reducing filters.
 10. Apparatus according to claim 5 wherein said fluid is air. 